1. Field of the Invention
The present invention relates generally to an ultra high molecular weight composite material which is used on the deck plate of a ship as a non-skid surface. More specifically, the present invention relates to a hold device which secures an ultra high molecular weight composite material to the deck plate of a ship and allows for thermal expansion of material without damaging the material.
2. Description of the Prior Art
Presently, Naval watercraft and ocean going vessels are using ultra high molecular weight (UHMW) composite materials fastened to the deck plate of the watercraft as a non-skid surface for the deck plate. The UHMW composite materials provide an extremely durable non skid surface.
The UHMW composite materials are supplied to the Navy in large sheets which are fastened to the deck plate of the watercraft using welded studs, washers and nuts countersunk into the deck plate. Location of holes in the UHMW composite material and the studs in the deck plate is precise since the holes and the studs must be aligned prior to securing the UHMW composite material to the deck plate. Repeated expansion and contraction of the composite material due to temperature variations stresses the studs which often fail before the UHMW composite material reaches five percent of its useful life.
This attachment method requires unnecessary precision to secure the UHMW composite material to the deck plate and does not allow for thermal expansion of the material.
Accordingly, there is a need for a very simple and highly effective device to secure UHMW composite material to the deck plate of watercraft which allows for thermal expansion of the material without separation of the material from the deck plate.
The present invention overcomes some of the disadvantages of the past including those mentioned above in that it provides for a relatively simple in design, yet highly effective hold down device which is used to secure a UHMW composite material to the deck plate of a watercraft and to vertical structures of the watercraft. The hold device of the present invention also allows for thermal expansion of the composite material without separating the composite material from the deck plate of the watercraft.
The hold down device includes a base, attached to the deck plate, and a hold down plate secured to the base by a threaded screw. The hold down device allows for thermal expansion of the UHMW composite material which prevents the UHMW composite material from separating from the deck plate.
A UHMW hole cutter tool is used to cut an opening in the composite material which allows a user to weld the base of the hold down device to the deck plate of the watercraft. An upper portion of the opening has a greater diameter than the lower portion of the opening in the UHMW composite material formed by the cutter tool on the UHMW composite material. The base of the hold down device fits within the lower portion of the opening and is secured to the deck plate by electric welding.
When the hold down device is fully assembled, the hold down plate is positioned on a ledge formed on the UHMW composite material between the lower and upper portions of the UHMW composite material which secures the material to the deck plate.